Slow break switch



April 1939- R. F. SAMBLESON 2,153,396

SLOW BREAK SWITCH Filed Nov. 9, 1937 Fig.3. F1534.

lnverwtorfi a l Rgbert F. Sam blesorw,

His Attorney.

' Patented Apr. 4, 1939 greases stow BREAK swrron New Yorlr Application November 9, 1%2, Serial No. ll'itfiid 4 Claims.

This invention relates to switches oi the slowbreak type for use with alternating current.

It is an object of the invention to provide an improved construction and arrangement oi 5 switches of this type wherein means are provided a to separate the switch contacts a small distance until the current wave passes through a zero point thereby interrupting the current and. ex tinguishing the arc across the contacts occasioned by the current interruption Referring to the drawing, Fig. l is an elevation of the assembled switch; Fig. 2 is a vertical sec- 3 tion through the switch; Fig. 3 is a sectional view through the switch in closed position partly along the line 3-3 of Fig. 1; Fig. i is'another sectional iii view through the switch in open position partly.

along the line Q5 of Fig. 2; and Fig. 5 is a perspective view of the switch actuating mechanism.

The switch, as shown in Figs. 1 to i, inclusive, has a housing it formed of molded composition, or the like, which is provided with a bottom it having upstanding abutments l2 and I3 at each end adjacent the end walls it and I5, respectively. The abutment i2 and the wall Hi form a reswitch blade ill.- The blade it is formed of a strip of spring bronze and is bent at an angle, as best shown in Figs. 3 and 4, and placed within the housing with the terminal end seated in the recess it with the sides in close engagement with the abutment l2 and end wall I4. Inthis mannor the blade is held securely within the housing without the use of separate fastening means such as rivets, or the like. Similarly, the abutment l3 and end wall l5 form a recess l8 adapted to receive the terminal end of a bronze switch blade l9 which is bent at an angle and disposed in the housing l along side the blade ll. The abutment i3 and wall l closely engage the blade l9 when it is inserted into the recess l8 and hold the blade securely within the housing. The blades ill and 19 are provided with terminal screws l1 and It for connection to a line circuit, the heads of the screws being disposed in recess l4 and I5 formed in the end walls l4 and 15.

In order to prevent the blades I! and I!) from becoming unseated from the recesses l6 and I8 and in order to enclose the switch mechanism, the housing is provided with a cover 20 which engages the upper edges of the blades and retains them in the recesses. The cover may be formed from sheet fiber and is clamped to the top of the housing by means of a bracket 21 having clamping prongs 22engaging in grooves 23 formed in the side walls 24 and 25 of the housing. Each cess it which receives the terminal end of a side wall is formed with ribs extending into the interior of the housing, the ribs giving the side walls a thickness sufficient to provide for the grooves 23 which are formed within the ribs 26. The grooves extend from the bottom of the casing to a point short of the top where they terminate to form engaging surfaces for the bent-over portions 2i of the prongs 22. To provide a supporting means for the switch a threaded sleeve is is mounted upon the bracket 20 and is secured thereto by a bent-over flange 29.- The sleeve may be inserted into an opening in a mounting panel;

or the like, and secured to the panel by a nut (not shown) threaded upon the sleeve.

The mechanism for operating the switch blades includes a handle 3t pivoted within the sleeve 28 by a pin 3!! and adapted to oscillate within the walls of the sleeve from off to on position. Depending from the handle 3% is a switch blade actuating arm 32 and a slider 33 both of these elements being mounted on the pin 3! and being fastened to the handle by means of the crimpedover projections 3d, shown in Fig. 5. The slider and actuating arm are in intimate contact and oscillate as a unit with the handle 30. The actuating arm 32 is formed of insulating fiber and carries at its outer end a projection 35 having a shank 36 passing through the arm and being secured thereto by means of an upset head 31. The head is housed within an opening 38 formedin' the slider 33; this construction permits the slider and arm to lie fiat against each other and forms a protecting wall for the projection head. The

- slider 33 is punched from insulating fiber, paper, or the like. To insure proper engagement between the slider and the switch blades the arm 32 is formed with a cutout recess 32.

Figs. 3 and 4 illustrate the manner in which the slider and projection cooperate with the switch blades. The switch blades l1 and I9 are provided with opposed contacts 38' and 39 which may be made of copper coated with silver and which are normally in engagement under the spring action of the switch blades, as shown by Fig. 3. In addition, the switch blade l9 isprovided with a depression 40 to receive the projection 35, together with a cam or inclined surface M which likewise coacts with the projection. To support the projection against the blade the housing I0 is formed with a bearing surface 42 upon which the slider 33 and arm 32 rest so that the projection 35 is disposed between the blade l9 and the surface 42.

With the contacts 38 and 39 in engagement the switch is closed and the handle 30, together added precaution in case the spring contact IS with the slider 33 and actuating arm 32, take the position shown by Figs. 1 and 3 with the projection 35 in engagement with the inclined surface ll of the blade l9. As the switch is moved to "open" or "off" position the projection 35 moves along the inclined surface 4| and by bearing against the surface 42 springs the blade ll thereby opening the contacts 38 and 39. The contacts need be opened a small distance, only, to cause opening of the circuit, because as the current wave passes through a zero point the current flow across the contacts will be interrupted. In like manner, any arc which may be formed between the contact points .will be extinguished immediately as the current wave passes through a zero point. By opening the contacts a small distance, only, a minimum of energy is released in the arc during separation of.

the contacts. As the projection moves along the spring blade the insulating slider 33 will be inserted between the contacts 38 and 39 as they are sprung apart, the slider thus acting as an additional safeguard in extinguishing the arc. In this position the actuating arm 32 will straddle the contact I! the latter nesting in the recess 32' cut from the actuating arm.

Theoretically, it is not necessary to interpose the insulating slider between the contacts in order to extinguish the arc; this is done as an loses its temper, and separation of the contacts by projection 35 is not to be relied on. However, the slider will act to extinguish the arc in cases where the switch is operated extremely fast so that the time of switch travel is less than the time interval of a half cycle of the current.

.In addition, the slider acts to clean the contacts as it is moved to and fro over their surfaces.

Further movement of the switch handle permits the projection 35 to center itself in the depression 40 thereby holding the switch in off position and allowing the contact 39 to close toward the other resiliently clamping the insulating slider 33 between the contacts. This position is shown by Figs. 2 and 4.

In spite of the fact that the switch is operated by hand it is notpossibleto leave it partially opened. The switch is either "on" or "011. If the projection II is left halfway along the in- 60 surface 4| the spring action of the blade I9 will cause the projection to move along the surface to the left in Fig. 3, to permit the contacts to close. However, if the projection is left in mid-position on blade i9, it will remain there and the switch will remain in the 011" position.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a switch, a housing having a bearing surface therein a fixed contact member and a movable contact member, said movable contact member having a cam portion, cam-operating means movable along said bearing surface and coacting with said cam portion to separate said contacts, an insulating slider movable co-extensively with said means and adapted to be inserted between said contact blades when in separated position, and means to move said cam-operating means and slider.

2. In a slow-break switch, a fixed contact member and a movable contact member, said 'movable contact member having an inclined portion and a depressed portion, operating means including a projection movable along said inclined portion to separate said contacts, and an insulating slider movable co-extensively with said projection, said operating means being adapted to insert said slider between said con tacts and simultaneously position said projection in said depressed portion.

3. In a switch, a fixed blade and a movable blade, opposed cooperating contacts mounted on said blades, said movable blade having a cam surface and a depressed portion, a pivoted arm, a projection mounted on said arm and cooperating with said cam surface to open said contacts, a pivoted insulated member movable with said arm and insertable between said contacts as said abutment moves alongsaid cam surface and into said depression, said arm having a cutout portion to receive said movable contact, and means for moving said arm and member.

4. In a slow break switch, a housing having a bearing surface therein, contact blades mounted in said housing, one of said blades having a cam surface, a projection movable along said bearing surface and engaging said cam surface to open said contact blades, and means to operate said L projection.

. ROBERT F. SAMBLESON. 

